Mixing services within MPEG/DVB transports streams for distribution within the digital tier can require editing of elementary services and associated tables. Downstream equipment is not always interoperable and may expect a very specific assignment of packet IDs (PIDs) and program numbers further complicating the editing process. Traditional solutions apply point-to-point mapping of PIDs for each installation. The input programs and elementary service PIDs are mapped to output PIDs and programs. Any subsequent change on the input side such as a change in the program or referenced elementary services is not necessarily reflected on the output side. Therefore, PID point-to-point remapping unfortunately inhibits several features dependent on dynamic transport changes such as re-tuning, channel changing, service replacement (S/R), and automatic mapping of elementary services as they are added.
Existing remapping controls provide for only manual mapping modifications in the event of, for example, a channel change, selection of a different transport, or when new services are to be added to a program. Manual updates such as channel changes by installers require some knowledge of the transport change and, therefore, the opportunity for installer error is significant for installation change. This is because PID reassignments are specified on an individual basis and every such change must be entered manually. Therefore, burdensome operator invention is often necessary with manual point-to-point remapping which is undesirable.
As a further example, Service Replacement (S/R) is an independent control mechanism that was developed as a means of temporarily switching baseband content at downlink sites. The channel number change as a result of the S/R is not presented to the end user during the switch to alternate programming. In the case of S/R for which any service interruption carries negative consequences, manual intervention is more than undesirable; it is unacceptable from a service provider's point of view.